Assessment of RELAP5/MOD2 Computer Code Against the Natural Circulation Test Data from Yong–Gwang Unit 2 (NUREG/IA-0125)

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Publication Information

Date Published: June 1993

Prepared by:
N. Arne, S. Cho
Korea Electric Power Corporation
Research Center
117–15 Yongjeon–Dong, Dong–Gu
Daejon, Korea

H. J. Kim
Korea Institute of Nuclear Safety
P.O. Box 16, Daeduk–Danji
Daejon, Korea 305-353

Prepared as part of:
The Agreement on Research Participation and Technical Exchange
under the International Thermal-Hydraulic Code Assessment
and Application Program (ICAP)

Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

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The results of the RELAP5/MOD2 computer code, simulation for the Natural Circulation Test in Yong-Gwang Unit 2 are analyzed here and compared with the plant operation data. The result of comparison reveals that the code calculation does present well the overall macroscopic behaviors of thermalhydraulic parameters in primary and secondary system compared with the plant operating data. The sensitivity study is performed to find out the effect of steam dump flow rate on the primary temperatures and it is found that the primary temperatures are very sensitive to the steam dump flow rate during the Natural Circulation. Because of the inherent uncertainties in the plant data, the assessment work is forcussed on phenomena whereby the comparison between plant data and calculated data is based more on trends than on absolute values.

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